Computer-assisted welding process and system, based on a view of the welding scene

Abstract

Computer-assisted welding process and system, based on a view of the welding scene. This invention relates to a computer-assisted welding process and system. This automatic welding process, assuring the processing of images taken during a welding scene, is based on a learning from the welding cases already processed. It comprises the operations for prior establishment of relationships between the parameters of welding; of installation, in hardware or software form, of these relationships in a welding system, then the execution by this system; of pictures of a welding scene in progress; of analysis of each of these pictures to measure certain of the welding parameters; of evaluation, from these relationships, of values for correction of the welding parameters; of intervention, as a function of this evaluation on the welding in progress. This process is used by a system having a welding head able to take the pictures, and a processing and control unit able to apply said process. This finds numerous applications all high-technology industrial fields, such as the aeronautics and nuclear fields.

We claim: 
     
       1. An automatic welding process in which welding parameters are processed that vary during an execution of welding, comprising: establishing a first stage of relationships by establishing at least one data base from triplets of parameters wherein each triplet comprises a measured parameter, a controllable parameter, and a result parameter, and further wherein aid data base is constructed from data acquired during a prior welding operation between said welding parameters and storing these relationships, the first step of establishing said stages of relationship comprising establishing three data bases:   a static data base comprising, for each of the measured parameters, values obtained for the controllable parameters and the result parameters under established conditions;   a dynamic data base comprising values of the measured parameters and the result parameters during temporary variations of the controllable parameters; and   a disturbed data base comprising values of the result parameters obtained from the measured parameters and the control parameters in the presence of a disturbance to be treated; and   a second stage wherein said second stage comprises the steps of a) employing a CCD imager to take visible image pictures of a welding scene in progress including a frontal portion of said welding scene by use of light produced by said welding scene;   b) analyzing said visible image picture-taking to measure the welding parameters affecting the relationships;   c) evaluating from these measurements and from said relationships, the correction values to be made to the welding parameters; and   d) intervening, as a function of said correction values, on the welding in progress.     
     
     
       2. A process according to claim 1, further comprising the step of between operations (a) and (b), creating a dialog operation with a user for assuring a choice of automatic execution or of interactive execution of operations (b) to (d). 
     
     
       3. A process according to claim 1, wherein the operations constituting the second stage are continually repeated as long as an interrupt order has not been received. 
     
     
       4. A process according to claim 3, wherein the interrupt order is given by a user during an interactive dialog operation. 
     
     
       5. A process according to claim 1, wherein picture-taking operation (a) is followed by a storing of said visible image picture taking. 
     
     
       6. A process according to claim 1, wherein said first and second stages of relationships comprise relationships between a measured parameter with a result parameter. 
     
     
       7. A process according to claim 6, wherein said first and second stages of relationships comprise connecting a relationships between a result parameter with a controllable parameter, correcting each result parameter subject to an appropriate constant value of the controllable parameter from the determination of the measured parameter. 
     
     
       8. A process according to claim 1, wherein said first and second stages of relationships comprise relationships between a result parameter and a controllable parameter. 
     
     
       9. A process according to claim 1, wherein stages of relationships between parameters comprise a relationship describing a width of a welding bath. 
     
     
       10. A process according to claim 1, wherein stages of relationships between parameters comprise a relationship describing a contour of the welding bath. 
     
     
       11. A process as in claim 1 further comprising performing said welding operation in a melting bath. 
     
     
       12. An automatic welding system comprising: a welding head;   a welding carrier to which the welding head is fastened;   means for supplying the head with electricity; and   a processing and control unit connected to the welding head and to the carrier, wherein, the welding head further comprises means for taking visible image pictures of the welding scene and for detecting at least one of a profile and a width of a welding bath using only light produced from said welding scene,   the welding carrier being configured to be moved relative to the welding scene, and   the processing and control unit comprising, a central processing unit means for analyzing the pictures, and   means for controlling a power supply means and the welding carrier.       
     
     
       13. A welding system according to claim 12, wherein the processing and control unit further comprises means for displaying images and means for storing said images, located upstream from the analysis means. 
     
     
       14. A welding machine according to claim 13, wherein the means for analyzing the images of the welding scene comprises an image acquisition card installed in the central processing unit (CPU), this card being connected to the means for displaying images and to the means for storing images. 
     
     
       15. A welding machine according to claim 12, wherein the central processing unit comprises: input/output interface cards able to establish connections between the CPU and the welding carrier, between the CPU and the power supply means and between the CPU and the welding head.   
     
     
       16. A welding machine according to claim 12, wherein the electric power supply means comprises a welding generator generating a welding current that can be controlled from the outside by at least one electric signal. 
     
     
       17. A welding machine according to claim 16, wherein it further comprises means for regulating an arc voltage that is connected, at input, to the welding head, and, at output, to the welding carrier.